It is very obvious that Argentina has such players in abundance and clubs should be sending scouts over there to acquire such players.
Alternatively the French league seems to a breeding ground for such players but they usually of African origin not French. But they tend to ply their trade in France as Claude Makele, Saydoo Keita, Mohamadoo Diarra etc to name a few.
As far as the creative midfielder goes, the 1st point of call should always be Brazil as they produce them more than any other country with Argentina being another country that produces them in abundance but their creative players tend to be more strikers than attacking midfielders.
As far as strikers, goalkeepers, defenders go, there does not seem to be a country that has the monopoly on those positions as it depends on the type you want but I would not go for a Portuguese for a striker as there are not any.
I would bypass the English and Argentines if I wanted a decent goalkeeper as they are very few and far between and it is not a good idea to go for a Spanish defender as Carlos Puyol and Sergio Ramos apart, there are not that many if any world class defenders about.
As far as the manager is concerned, I would not go for an Italian because they are too technical and do not let their teams express themselves enough and definitely not an Englishman as they are not technical enough.